By Valeria Palomba, Andrea Frazzica, Steffen Kühnert, André Große

Last September our colleagues Valeria Palomba, Andrea Frazzica, Steffen Kühnert and André Große
presented the following paper on Hycool at the Eurosun conference held in Rapperswill:

ABSTRACT

This paper presents the dynamic modelling of a hybrid cascade chiller for solar cooling in industrial applications driven by Fresnel solar thermal collectors. The chiller comprises an adsorption module, which is directly connected to the bottoming vapor compression chiller. This cascade configuration allows enhancing the overall electric COP, since the adsorption module is operated to dissipate the heat rejected by the vapor compression chiller, thus reducing the condensation temperature quite below the ambient temperature. The model was implemented in Dymola/Modelica, allowing describing heat and mass transfer phenomena inside each component. The complete model was then validated against experimental data obtained on a cascade chiller prototype at the CNR ITAE lab. Finally, a reference daily simulation was performed to evaluate the ability of the developed chiller in providing cooling energy to a typical industrial application

Keywords: Dymola/Modelica, cascade chiller, industrial solar cooling

1. Introduction

The cooling demand is continuously growing worldwide in different sectors (Werner, 2016). Particularly, energy consumption and related emissions due to cooling processes in industrial sector are becoming a major issue. For this reason, the integration of renewable thermal energy sources inside industrial sites, for both heating and cooling applications is gaining a lot of attention (Farjana et al., 2018). Usually, it is accomplished with the use of thermally driven sorption machine, driven by thermal energy produced by non-concentrating solar thermal collectors (e.g. flat plate, evacuated tubes) (Murray et al., 2016). Nevertheless, this approach suffers of some weaknesses: first, when renewable source (i.e. solar energy) is not available, a backup system is needed to either operate the sorption chiller (e.g. gas boiler) or to directly produce cooling by means of standard technology (e.g. vapour compression chiller).
Secondly, the use of non-concentrating solar thermal collectors technologies often is not sufficient to properly drive the sorption machine, thus making it work under off-design conditions for several hours. Furthermore, these solar thermal collectors cannot be integrated as heating source in most of the industrial sites, since the achievable temperature level is usually not sufficient drive any process.

In such a background, the EU co-funded project HyCool (HyCool, 2018) aims at increasing the use of solar heat in industrial processes, integrating a concentrating Fresnel solar thermal collector technology, with a hybrid cascade chiller, to increase the share of renewable sources for heating and cooling applications in industries.

The present paper deals with the development of a numerical model, implemented in Dymola/Modelica, for the simulation of the innovative cascade chiller. The model describe heat and mass transfer phenomena in each component of the chiller, in order to accurately simulate its operation. Furthermore, it has been validated by means of experimental data measured at the CNR ITAE lab and it will be further used to evaluate optimal operating conditions and management strategies under typical working boundaries of an industrial plant.

2. The Hybrid cascade chiller

The hybrid heat pump is made up of two units, working in cascade mode: a thermal unit and an electric unit. The thermal unit is an adsorption chiller, based on the system already commercialised by Fahrenheit, which will be driven by the heat produced by a field of Fresnel solar thermal collectors, for the production of chilled water in the range of 16-22°C. This unit is hydraulically connected to the condenser of an electric vapour compression unit (i.e. cascading mode), which will provide chilled water to the user. In such a way, the adsorption unit is primarily meant for dissipating the condensation heat of the vapour compression unit. This operation allows increasing the overall electric COP, by reducing the temperature lift between evaporator and condenser of the vapour compression unit, thus limiting the compressor work.

Furthermore, the utilization of the cascading operation of the two units allows exploiting the benefits of the two types of systems, i.e. the low primary energy consumption of the thermal unit, which will be fed by renewable solar energy, and the fast response and good temperature control under different conditions of the electric unit (Vasta et al., 2018). A schematic of the hybrid heat pump operation and components as well as the different temperature levels is reported in Figure 1.

3. Dynamic modeling and validation

As shown in Figure 1, the hybrid heat pump is realized by hydraulically connecting the thermal and electric units. Consequently, the models for the two units were implemented and tested separately and then the overall model for the system was assembled and calibrated. […]

BY SILVIA JANÉ (European Projects Manager), VEOLIA SERVEIS CATALUNYA

The food sector is making ever increasing demands for cooling in production and product conservation processes. Such a situation represents a challenge to the industry, since higher energy consumption can lead to increased greenhouse gas emissions (CO2, SO2 and NOx), which in turn contribute to global warming of the atmosphere. The HYCOOL project was born from the need to cope with sector demands and to minimise their environmental impact. The aim of the project is to maximise the use of renewable energy sources in industrial cooling.

HYCOOL (Industrial Cooling through Hybrid system based on solar heat) is an innovative project co-financed by the European Union as part of the Horizon 2020, programme for validating an industrial cooling and steam generation system using high temperature solar panels. The project, which commenced in May 2018 and is set to last for three years, is led by Veolia Serveis Catalunya and is made up of another 16 partners from six European countries. HYCOOL has a budget of 7.7 million euros and will be tested in two industrial plants in Catalonia.

The aim of the HYCOOL project is to increase the use of solar heat in industrial processes and show that it is feasible to apply new technologies (understood as a system) to industries with cooling needs with the use of solar energy. One of the advantages offered by HYCOOL is its greater flexibility and capacity for adaptation to different settings thanks to its hybrid pumps, which enable it to work with conventional grid electricity or from renewable systems such as solar energy. Hybrid pumps also provide a more efficient system by doubling the coefficient of performance (COP) of conventional heat pumps.

The advantages of HYCOOL for the food industry

One of the sectors that can most benefit from application of the HYCOOL system is the food industry, since it permits the current recooling plants to be replaced. Such plants are necessary for extracting heat from the production areas or for reducing and/or maintaining the temperature of the food product at low temperatures before, during and after the production process.

The purpose of the cooling required in the food industry is to reduce biochemical and microbiological changes in foodstuffs. This enables the life span of fresh produce and processed foods to be lengthened and can also maintain a given temperature during processing, as is the case in fermentation processes.

There are a multitude of processes in the food sector that require cooling systems, as is the case in the fermentation industry (such as the beer-making sector in their fermentation processes, yeast tanks and product storage), the dairy industry (milk pasteurisation processes, obtaining and concentrating whey, butter production, etc.), the meat processing sector (packaging processes in production and storage of raw materials and end products) and the bread industry (fermentation and storage), etc.

For processes like these, the set point temperatures are variable, which is the case with cooling systems used in the market (evaporative cooling systems, indirect cooling, etc.). The HYCOOL system can reach temperatures of 5ºC or -10ºC, depending on the configuration of the compressor it uses (cascade or pre-cooling mode), which makes it adaptable to almost any process in the food industry.

Bo de Debò: first food company to try out HYCOOL

The expectations for the HYCOOL system are not humble ones: it is hoped that the system shall enable reductions in energy consumption of around 75% and increases in efficiency of 25% in the environments where it is used. To demonstrate this, the company BO DE DEBÒ, in Sant Vicenç de Castellet (Barcelona) was selected as a firm in the food sector to test HYCOOL and confirm the performance expected from the system. The main focus of the activities of BO DE DEBÒ is on preparing high-quality pre-cooked dishes, which requires cooling to be used in its conservation processes for raw materials and end products (between 0 and 4ºC) and in the production and delivery areas (between 8 and 12ºC).

The cooling system operates via solar energy and has two key components: the collectors and the hybrid heat pumps. The Fresnel compact solar collectors -developed by the Austrian company, FRESNEX– have a mirror surface area of 10 m2 and supply the heat source used by the system. They also incorporate a swivelling mirror bearing as the support bearing system for the mirrors, using a hinge line. This innovative feature enables the element’s thermal performance to be increased, as demonstrated in the test institute, where excellent results were obtained. On the other hand, the hybrid heat pumps (or HHP) developed by the German company, FAHRENHEIT are made up of a hybrid adsorption/compressor cooler that can exploit thermal energy (residual heat or other renewable energy sources) and electrical energy to supply cooling energy with high electrical efficiency. The system includes an adsorption module with an evaporator that cools the steam compression cooler condenser, thus improving the electrical COP.

Concentrating solar collectors

Schematics of the cascading hybrid heat pump and 3D rendering of the aggregate of cascaded hybrid heat pump with a nominal cooling capacity of 10 kW.

The combination and flexibility offered by the system makes for a wider range of output temperatures, generating a broader spectrum of applications in industrial processes. All these technological innovations shall be put to the test at BO DE DEBÒ, which has a solar field surface area of 400 m2 and receives personalised implementation according to its needs.

Other systems that the system can include are steam generation or uses with hot domestic water, or dissipation systems for heat generated in months when most heat is generated and in new processes. Regardless of the use it will finally be put to, the HYCOOL project aims to show that the system’s flexibility enables it to be adapted to any surroundings and so obtain satisfactory performance.

Veolia’s commitment to promoting this type of projects demonstrates the desire of the company to innovate and constantly seek environmentally sustainable solutions based on renewable energies. The implementation of the HYCOOL project is one example of how collaboration between government and the business community can give form to initiatives that not only mean improvements in a company’s energy consumption results but also in its impact on the environment.

The HYCOOL consortium successfully held the 1st General Assembly on 22 and 23 November 2018, in Messina, Italy. The meeting was kindly and efficiently organized by CNR – ITAE.

As a presentation, Andrea Frazzica from CNR – ITAE opened the General Assembly meeting on the 22nd with a brief introduction about the institution’s activities and the city of Messina, and right after Ferran Abad from Veolia presented a note on the general project status in relation to the designs of the pilots and the specification of the technical solution.

After the presentation, during the first day, all partners got an overview of the HYCOOL project and its different work packages and had several meetings to clarify some technical points and also some issues related to the management of the project, closing the long day with a truly pleasant social dinner organized by the partners of CNR-ITAE.

During the second day, partners were able to review the project’s dissemination and communication activities and also attended a presentation on the Open Access principles, very useful for future project publications.

Silvia Jane and Ferran Abad from Veolia closed the meeting by reviewing all tasks, responsibilities and deadlines and summarizing the most important issues raised during the meeting.

Why do you think Hycool is a necessary European project in the current context?

DM (INEA): It is crucial that EU academic, research and industrial sectors join forces with the aim of demonstrating that solar heat can be a reliable energy source for industrial processes, therefore bringing significant prospects for the market uptake of this renewable energy source and for the decarbonisation of industrial processes.

What were your impressions at the kickoff meeting?

DM (INEA): I was impressed by the individual capacities brought up to the consortium by each member, but also aware of the big technical, administrative and management challenges to be faced by the project during its lifetime due to several aspects such as the large size of the consortium or the relatively short duration (36 months) for a project of this type. The consortium will receive 5.8M€ of EU taxpayer’s money that this is a big responsibility for the project to get timely results.

What is the interest of the project having a consortium with a mix of small and large companies?

DM (INEA): One of the main objectives of Horizon 2020 research and innovation programme is to bridge the gap between science, research and innovation communities and society at large by fostering more inclusive, anticipatory, open and responsive research and innovation systems. In other words, bring solutions to the challenges faced by society from research to market. In this frame, it is very interesting to have an adequate mix of small and large companies in order to ensure the SMEs are ready to scale up their technology once it is validated in the project but also that significant industrial investment effort is ensured during the project and after its completion by the different large companies in the consortium.

What achievements do you expect from Hycool, and what impact do you think they could have on both industry and the environment?

DM (INEA): From INEA we expect the project to fulfill the obligations set out in the Grant Agreement signed between both parts. In particular, the main achievements should be to improve industrial integration of current solar heating systems, to achieve a cost effective solution, and finally to demonstrate that solar heat can be a reliable energy source for key industries in terms of thermal energy consumption (chemical and food).

In the long term, the main impact of Hycool should be the contribution to the decarbonisation of industrial processes in view of the global environmental challenges faced by our society.

How do you think Hycool technology will benefit industries of its two particular demo cases?

DM (INEA): If successful, Hycool will result in significant savings in their cooling processes for both primary energy and fossil fuel utilization, with the corresponding economic impact this will entail. In addition, both companies could also benefit from a positive impact on the public perception of their activities, which will help improving their core business.

How do you see the replication of the Hycool project results to other industrial sites?

DM (INEA): I see the replication in different industrial sites as the next necessary step after the project lifetime. I think the strong interest and capacities brought up by the partners involved in the project and the one gained during the 36 months duration will ensure the replication of the Hycool solution, therefore bringing significant economic and environmental impacts to other industrial sites.

Last June Fresnex presented the HyCool project at the CIES 2018 in Madrid (XVI Congreso Ibérico y XII Congreso Iberoamericano de Energía Solar), the most important solar energy congress in the Spanish and Portuguese speaking countries. In this congress, the most interesting and novel projects related to all major solar technologies are presented and discussed, with the presence of the all relevant stakeholders from the sector.

Fresnex is an Austrian manufacturer of solar concentrating technology based on an innovative approach using flat solar mirror modules to concentrate the sun on a receiver. The Fresnel based concept to provide concentrated solar heat (CSH) is a major pillar of the HyCool hybrid solar heating and cooling project. It was developed specifically for process heat in the industry, is ideal for rooftop applications and aims to drastically reduce the costs of solar heat thanks to its patented technology. The company was invited to present its latest developments and upcoming projects in Spain. During the speech, Fresnex briefly described the HyCool project and the corresponding implementation in two industrial demonstration sites in the area of Barcelona.

Fresnex is playing an important role in the introduction of effective CSH projects in industrial applications in the European market. Each installation reduces substantially the consumption of fuel fossils for thermal applications in the industry, generating both a positive impact in the reduction of greenhouse gas emissions and real savings in the industry’s yearly fuel bills. Both HyCool demonstrators will prove for the first time in Spain the real potential of CSH in the industry. They will mainly generate solar steam, solar hot water as well as solar cooling in combination with novel phase change storage technologies.

HyCool project was presented during the Sorption Friends Workshop held in Pisa (16-18 July). Dr. Uli Jakob took the chance to present the HyCool project during the “Flashlight” session with about 65 participants from all over the world (Europe, Canada, USA, Russia, India, Japan), including members from CNR and Fahrenheit – which are also part of the HyCool consortium.

Market perspectives, segments, requirements, competing technologies and means were discussed and summarized in various working groups looking among other things into cooling applications (residential sector with single, multi-family houses and districts as well as light commercial buildings) and industrial cooling applications.

The results of the Sorption Friends Meeting, and all the information coming from the workshop are important for the future HyCool market analysis and the market integration of the developed systems.

The Innovation and Networks Executive Agency (INEA) which was created by the European Commission in 2006 to manage the technical and financial implementation of Smart, green and integrated transport + Secure, clean and efficient energy programmes, invited the HyCool coordinator to the 2nd clustering meeting on Horizon 2020 projects in the area of Concentrated Solar Power. The meeting was held on June 26th 2018 in the INEA premises (Brussels).

The projects reported on their current results and will explore possibilities for collaboration and synergies, including the organisation events or workshops. In this sense, Hycool project manager presented the project and the main objectives with the aim to update the European Commission officials and to discuss the advancements in the sector; the progress achieved so far will be shown after the first year of the ongoing project.

After this, a discussion on potential synergies/overlaps & opportunities with the objective to develop ideas for further joint activities, identified from the project presentations, took place, as well as a discussion in the working groups with mixed representatives of different types of projects.

The different groups will work together in the next 18 months with the action points defined during the meeting where Hycool identified two projects with synergies & opportunities: the Ship2Fair and Inship projects.

HyCool project was invited to participate in Sustainable Places 2018, an annual international conference who gathers stakeholders from leading organizations around the world to advance the state of art and play in one of the greatest challenges that our societies and their urban planners have ever faced: The need to enhance the sustainability of places ensuring long-term environmental security.

The event was held from 27th to 29th of June, and the local co-hosts for this 6th iteration of the congress were INES (The French National Solar Energy Institute of France) and University Savoie Mont Blanc (Chambery campus). The general SP2018 program structure included atwo-day symposium, comprising several keynote speakers, clustering workshops, and presentation sessions.

Even the event was just about one month before HyCool’s KoM, so we could just provide general information about the project, it was a great opportunity to start with the project’s dissemination, contributing with a poster.

The 1st HyCool General Assembly was held on May 17th and 18th in the HOTEL FIRA CONGRESS (Barcelona). Ferran Abad from Veolia Serveis Catalunya, as a Coordinator, opened the meeting at 9:00 following with the presentation of partner’s institutions, the main working interests detailing the interest in HYCOOL and the related activities and the expectations concerning project actions and outcomes.

It was a pleasure to have the participation of Daniel Maraver as a Project Officer from INEA, who explained the administrative issues to the Consortium and helped to better understand the aspects related to the European Commission programmes, the INEA and Horizon2020 and the implication and roles concerning the grant agreement and the expectations on the works to be carried on.

Following this, Silvia Jane as a Project Manager from the Coordinator entity presented the project overview and structure, understanding the general objectives of the project including the submitted proposal mission, the general objectives and specific technical objectives, the key equipment, the risk monitoring and measures and some other general issues. Each leader of the work packages presented the major objectives and deliverables, what the WP expects from the partners, the immediate objectives (6-month plan) and the potential risks detected.

During the meeting of the two days of work, several topics were discussed for the start of the project, but the best opportunity was to meet the partners personally and be able to discuss all the concerns and peculiarities of the project. There was also time to get to know the city and converse in an environment outside of work.

Thank you all for the participation and collaboration during these two days. It has been a good start of the project that will continue during the three years of the young HyCool project.